The growing popularity of pick-up trucks, as evidenced by their increased percentage of total vehicle sales, has pointed out the need for a lightweight pick-up truck camper. The camper units currently available on the market, when fully equipped with appliances, are too heavy to be carried on the more popular full size pick-up trucks such as the Ford F-150, the best selling pick-up truck in the United States over the past several years. The pick-up campers available today, when equipped with a refrigerator, stove, toilet system, and water tank, weigh on the order of 1700 pounds, while the maximum weight capacity of the Ford F-150 is in the 1500 pound range.
While it would be advantageous to reduce the weight of a camper cabin, this is difficult to accomplish without sacrificing strength and rigidity. When the camper is mounted on the truck it derives substantial strength from the truck bed and chassis. But when removed from the truck bed and supported on jack stands or blocks the camper must still be rigid enough to withstand normal usage. This requirement has driven most prior camper designs to use a relatively heavy frame, usually made of metal, as the primary load-bearing portion of the cabin structure.
Another critical factor in the design of recreational vehicle cabins is cost, and this is directly related to the production technique used. To achieve low cost, a production method should involve the assembly of a minimum number of parts and should not require a great deal of skilled labor to assemble and finish the cabin.
Several previous camper designs have attempted to reduce weight by using fiber-reinforced plastic (FRP) as the main cabin material. U.S. Pat. No. 3,879,240 issued Apr. 22, 1975 utilizes an exterior shell of FRP molded in several sections which are placed over a metal framework and bonded together with adhesive. Low density polyurethane foam insulation is then sprayed onto the inside of the shell in a thickness sufficient to cover the frame, with a thin second layer of high density polyurethane foam applied over the insulation to form the interior surface of the camper structure. This construction requires the fabrication of a relatively heavy and difficult-to-construct metal framework to provide the structure with rigidity. It also results in a somewhat uneven interior surface due to the inexact nature of the foam spraying process.
U.S. Pat. No. 3,652,119 issued on Mar. 28, 1972 discloses a telescoping camper cabin which pops up for use. Upper and lower cabin sections are produced, each consisting of an outer and an inner FRP shell with a metal framework trapped therebetween. Low density insulating foam fills the remaining space between the inner and outer shells. Again, the metal frame is the load-bearing portion of the structure.
In U.S. Pat. No. 4,314,726 issued Feb. 9, 1982 a cabin structure is disclosed that is made from a sandwich of rigid plastic foam between an outer skin of aluminum and an inner skin of wood. A high pressure forming process is required to produce this laminate, and many subsequent fabrication steps are needed to shape the material into a cabin structure.